The reliance on nuclear power as a method for power generation has increased in recent years due to a corresponding increase in the demand for electrical power throughout the world. Accordingly, the amount of spent nuclear fuel has increased along with the need for safe methods for long term storage and disposal of these radioactive waste materials. Ideal containers for storage and transport of radioactive waste should have the capability of safe containment for as many years as possible. There are however, significant safety issues involved in the safe long-term storage of spent nuclear fuel due to the high levels of uranium enrichment. Various approaches have been developed for the containment of spent nuclear fuel. Prior art references such as U.S. Pat. No. 6,125,912 to Branagan disclose advanced neutron absorber materials and a method of utilizing rare earth metals such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials having a combination of superior neutron capture cross sections along with enhanced resistance to corrosion and oxidative leaching. Still further, U.S. Pat. No. 6,730,180 discloses advanced neutron absorbing structural material for use in spent nuclear applications requiring structural strength, weldability and long term corrosion resistance. This particular reference is directed to a austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content. Other nickel-based alloys are also disclosed. In addition to the foregoing, U.S. Pat. No. 6,919,576 and which issued on Jul. 19, 2005 is directed to a composite neutron absorbing coating material applied to a substrate surface, and which includes neutron absorbing layers overlying at least a portion of the substrate surface, and a corrosion resistant top coat layer overlying at least a portion of the neutron absorbing layer. Optional bond coat layers can be formed on the substrate prior to forming the neutron absorbing layer. In this particular patent, the neutron absorbing layer can include neutron absorbing materials such as a gadolinium oxide, gadolinium phosphate, or gadolium in the form of a gadolinide dispersed in a metal allow mixture. The coating layers may be formed by a plasma spray process or a high velocity oxygen fuel process.
While the prior art patents have operated with some degree of success, the inventors have endeavored to try and identify a new neutron absorbing nuclear criticality control material which may, in powder form, be applied to structural internals of spent nuclear fuel packaging components by a thermal spray process and which operates with a greater degree of success. A neutron absorbing coating for nuclear criticality control therefore, is the subject matter of the present invention.